Rock drill



EQG'. G ARTIN- v2,296,817

RocK DRILL sept.' 22,1942. Y

Filed Nov. 1s, 1939 s sheets-sheet 1 Sept. 22, 1242. E. G. @mm 2,296,817

ROCK DRILL H Filed Nov. 16, 1939l 3 Sheets-Shec 2 im A Mm.

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E. G. GARTIN ROCK DRILL Sept.` 22,4 1942 Filed Nov. 16, 1939 3 Sheets-Sheet 5 no wiwi Patentecl Sept. 22, 1942 UNETED STATES TET QFFICE ROCK DRILL Elmer G. Gal-tin, Claremont, N. H., assignor to Sullivan Machinery Company, a corporation of Massachusetts 23 Claims.

This invention relates to rock drills, and more particularly to improvements in hammer rock drills of the self-supporting stoper type.

An object of this invention is to provide an improved rock drill. Another object is to provide an improved rock drill of the self-supporting stoper type having improved means for supporting the drill on the working face as Well as at its rear end abutment, so that an extremely stable support is attained. A further ob-ject is to provide an improved self-supported stoper rock drill having improved means for supporting and guiding the drill hammer motor during its movements toward and from the work. Still another object is to provide in a rock drill of the above character, improved fluid actuated means for supporting the drill on the working face, the supporting means being of a novel design and having improved fluid supply and control means. Still another object is to provide an improved uid control means for the drill supporting means whereby when the drill hammer motor is running, the support control means is positively locked against inadvertent release. A still further object is to provide an improved control valve means for a hammer rock drill of the above character whereby the flow oi iiuid to the drill may be controlled in an improved manner. Yet another object is to provide an improved reversible feeding means for a stoper rock drill of the self-supporting type whereby the drill hammer motor may be fed rearwardly as well as forwardly with respect to the work while the drill is at all times maintained supported at its remote extremities. Other objects and advantagesof the invention will hereinafter more fully appear in the course of the following description and as more particularly pointed out in the appended claims.

In the accompanying drawings there are shown for purposes of illustration two forms which the invention may assume in practice.

In these drawings:

Fig. l is a front elevational view of a stoper rock drill constructed in accordance with the preferred illustrative embodiment of the invention.

Fig. 2 is a side elevational view, partially in longitudinal vertical section, of the rock drill shown in Fig. 1.

Fig. 3 is an enlarged vertical sectional view taken in the plane of the sectioning in Fig. 2. showing parts in a different position.

Fig. 4 is a cross sectional View taken on line 4-4 of Fig. 3.

Fig. 5 is an enlarged cross sectional View taken substantially on line 5 5 of Fig. 2.

Fig. 6 is a vertical sectional View taken substantially on line 6-6 of Fig. 2.

Fig. 7 is a detail sectional View taken on line 'l-l of Fig. 6.

Fig. 8 is a view similar to Fig. 7, showing the control valves in a different position.

Fig. 9 is a detail sectional View taken on line 9 9 of Fig. 6.

Fig. 10 is a view similar to Fig. 9, showing the control Valves in a, different position.

Fig. 11 is a view similar to Fig. 6, showing the control valves in a different position.

Fig. 12 is a developed sectional View taken on line I2-I2 of Fig. '7.

Fig. 13 is a detail sectional view taken on line |3-I3 of Fig. 6.

Fig. 14 is a detail sectional view taken on line I4I4 of Fig. 6.

Fig. 15 is a detail sectional View taken on line |5-I5 of Fig. 11.

Fig. 16 is a detail sectional View taken on line I6-IE of Fig. 5, showing the throttle Valve in different positions as indicated at a and b.

Fig. 1'7 is a detail sectional view taken in the plane of line l'l-I'l of Fig 5, showing the throttle valve in different positions as indicated at a and b.

Fig. 18' is a detail sectional view taken in the plane of line l-IB of Fig. 5, showing the throttle valve in different positions, as indicated at a. and bf.

Fig. 19 is a View similar to Fig. 2, showing a modified form of construction.

Fig. 20 is a View similar to Fig. 3, illustrating details of the structure shown in Fig. 19.

Fig, 2l is a cross sectional View taken on line 2I--2l of Fig, 20.

Fig. 22 is a detail sectional View showing a portion of the iluid supply means.

In both illustrative embodiments of the invention the rock drill is of the stoper type, although it will be evident that various features of the invention may be embodied in rock drills of various other types.

In the preferred illustrative embodiment of the invention shown in Figs. 1 to 18, inclusive, the drill hammer motor is generally designated l, the feeding means generally designated 2, the Supporting and guiding means generally designated 3 and the fluid control means generally designated 4. The drill hammer motor is of a conventional design, actuated by pressure fluid, and comprising a motor cylinder 5 containing a reciprocatory hammer piston S for delivering impact blows to the shank f a usual drill steel 1 suitably supported within a front chuck housing 8 secured to the cylinder, Also secured to the cylinder is a rear head block containing the fluid control valve means 4. As the structure of the drill hammer motor does not per se enter into this invention, further description thereof is considered unnecessary,

The feeding means 2 is herein of the reversible type and comprises a reciprocable feed cylinder i0 containing a feed piston II having its piston rod I2 terminating in an abutment engaging point I3 providing the rear support for the drill. The drill hammer motor I is supported on the feed cylinder with its longitudinal axis in parallelism with the feed cylinder axis and is movable with the feed cylinder, and the front chuck housing 8 has a lateral projection lf3 having a bore I5 within which the forward portion 0f the feed cylinder It! is suitably secured. rl`he feed cylinder has a front flange i6 clamped in position by a sleeve I1 engaged by a detachable head iii suitably bolted in position.

Now referring to the improved supporting and guiding means 3, it will be noted that the feed piston rod l2 is tubular and has a bore i9 closed at its rear end by a plug 25, the latter having threaded thereto at 2I the abutment engaging point i3, Telescopically arranged within the piston rod l2 is a cylinder 22 having an integral rear piston head 23. The forward end of the cylinder 22 has a flange 2f! clamped against a shoulder 0n the sleeve I1 by a plug 25 threaded within the sleeve. Telescopically arranged within the cylinder 22 is a cylindric tubular supporting rod 21 having a rear piston head 23 and projecting axially through openings in the head I8 and plug 25 forwardly in advance of the feed cylinder. Secured to the forward end of the tubular supporting rod 21 is an abutment engaging point 29 providing the front support for the drill. The piston head 23 provides a partial rear closure for the tubular rod 21, as shown in Fig. 3. The plug 25 has a bore receiving a packing 30 for sealingly engaging the exterior of the supporting rod 21, while carried within a recess in the head i8 is another packing 3l. Arranged centrally within the cylinder 22 and extending within the supporting rod 21 is a stop rod 32 secured at 33 to the piston head 23, Integral with the forward end 0f the stop rod 32 and within the supporting rod 21 is an abutment or stop collar 34 with which the piston head 28 is engageable for limiting forward movement of the supporting rod 21 within the cylinder 22, thereby to prevent inadvertent withdrawal of the rod 21 from the forward end of the feed cylinder. To enable assembly of the rod within the cylinder and supporting rod, the piston head 28 has a slot 35 opening into a lateral enlargement 3S so that the abutment collar may be inserted within the supporting rod through the rear piston head 23. The collar is inserted through an enlarged end then moved laterally within the slot so that when the parts are assembled the collar is engageable with the sides of the slots. If desired the abutment collar may be detachably secured, as by threading, to the forward end of the rod, thereby eliminating the necessity of the slot and its enlargement, the rod at that time simply passing through an opening in the piston head 22, in an obvious manner. The rear end of the rod carries an expansible split spring collar 31 adapted to enter the bore 35 in the rear cylinder plug 2E),

and this collar 31 when it is received within the plug bore frictionally engages the bore walls to hold the cylinder 22 in its retracted position within the feed piston rod.

The fluid control means 4 comprises a throttle Valve of the sleeve type arranged in a transverse bore 4I in the rear head block 9. This Valve has a Valve stem to which is secured a control handle 42. Arranged in parallelism with the throttle valve bore in the head block is a conical bore 43 containing a conical control valve 44, the latter having a cylindric stem 45 slotted to receive the bent ends of a spring wire control handle 46. The head block is slotted at 41 and the handle projects out through this slot, and the slot is shaped to permit limited turning of the handle. The throttle valve 4i) has an internal uid supply chamber 48 to which pressure fluid may be supplied through a fluid supply connection 49. The exteriors of the Valves are grooved and their walls perforated by ports, as will later be described. For supplying pressure fluid from the supply chamber 48 to the feed cylinder bore at the forward side of the feed piston the throttle valve has its internal chamber connected by a port 5l) to an exterior circumferential groove 5I on the valve, and this groove is Connectible with a passage 52 in the head block, and passages in the cylinder and chuck housing connect the passage 52 to a port 53 (see Fig. 3) entering the feed cylinder bore at the front side of the feed piston I I. There is sufficient clearance between the exterior walls of the cylinder 22 and the bore of the feed piston rod I2, so that pressure fluid may flow from the forward side of the feed piston through the piston rod bore I9 to the rear side of the piston head 23, and, as a result, the combined pressure areas on the rear surface of the sleeve I1 and the rear surface of the piston head 23 act, upon pressure fluid supply thereto, to feed the feed cylinder, together with the hammer motor, forwardly toward the work. When the throttle valve is in the position indicated at a in Fig. 17, pressure fluid may be supplied through the ports and passages above described to the feed cylinder. When the throttle valve is in the position indicated at b in Fig. 17, the supply of pressure fluid to the feed cylinder is cut off and the feed cylinder is vented through a longitudinal groove 54 on the valve communicating with a fluid supply passage 55 of the hammer motor, as shown at b in Fig. 18, the feed being vented at that time through the motor exhaust. When the forward end of the feed cylinder is vented the pressure fluid in the piston rod bore I9 at the rear side of the piston head 23 is concurrently Vented and as a result the pressure iiuid in the cylinder 22, admitted to the latter in a manner hereinafter described, acts on the front pressure area of the piston head 23, and due to the differential pressure areas the cylinder 22 is moved rearwardly Within the piston rod bore. Since the cylinder 22 is secured to the feed cylinder IB, the latter moves rearwardly therewith to retract the drill hammer motor from the working face. The cylinders will move rearwardly until the piston head 23 engages the plug 20 at the rear end of the feed piston rod. When the throttle valve 4D is in the position indicated at a in Fig. 18, the vent groove 54 is cut oif from the motor supply passage 55 and the latter, as shown at a in Fig. 16, is connected to the supply chamber 48 within the throttle Valve by a port 56 traversing the walls of the valve. When the feed cylinder vent groove is vented through. the motor passage 5.5, the latter is cut on from the valve chamber 43, as indicated atb in` Fig. 16.. The reverse feed feature above described eliminates, particularly during horizontal. drilling, the necessity of manV ually moving the drill hammer motor in a rear- Ward direction, as would be necessary if the reverse feed feature Were omitted;

The valve 44: controls the flow of pressure fluid. to the cylinder 22 of the supporting and guiding means, and a passage -1 in the head1 block connects the supply connection 49 with the conical valve bore 43l (see Fig. 1l). The valve 44 has an axial bore 58l communicable through a port :'39 with the passage 5l'. A check` valve 6U arranged Within the valve 44 is held against its seat 6l by a coil spring, and pressure fluid may ow past this check valve to a recess 62 at an end of the valve. This recess is connected by a passageY 63 (see also Fig. 12) to a passage 64, the latter in turn connectedy by passages in the cylinder and chuck housing to a port 65V (Fig. 3) communicating through a recess 66- with the in-v terior of the support cylinder 22. The pressure fluid in the support cylinder 22" acts on the rear pressure area of the piston head 28 and the effective pressure areal on the forward Wall ofthe supporting rod bore', to effect movement of the supporting rod forwardly to bring the abutment engaging point 29 into engagement With the face of the work being drilled, While the abutment engaging point at the rear end of the feed pis-- ton rod is held against the rear end abutment and, as a result, the drill is heldl firmly in posi-v tion. In the event of failure of the pressure fluid supply for any reason, the check valve BEI will close automatically, thereby, to trap the-'pressurev fluid Within the cylinder'22 to prevent dropping away of the supporting rod 21 from the working face. For venting the fluid from the support cyli'nder 22 whenv the port 59 is cut off from communication with the port 5T, the valve 44 has a longitudinal groove 65 communicating With the recess 62 on the valve. When the valve 44' is closed the groove communicates with a vent port 63 (Fig. 7).

A lock is provided for automatically locking the valve 44 in open position during running of the hammer motor, comprising a locking plunger 69 reciprocable in a bore 10- arranged parallel with the valve bore and held in released"` position by a coil spring H (see Figs. 61-1, 12 and' l5) A passage 12 (Fig. l2) in the head block commu-nicates through a port 'f3 with the bore 1f! at the outer side of the plunger lock and through a port f4 with the valve bore 43 (Fig. 9). A circumferential groove l5 on the valve connects, when the latter is in the position shown in Fig. l0, the port 'i4 with a passage 16, the latter in turn communicating with a circumferential groove 'l1 on the throttle valve 4i). The groove 'H communicates through a port 18- with the valve chamberv 48. It is accordingly evident that when the' throttle valve 4e is in the positionV shown in Fig. 10, With the port 55 connecting the valve chamber 48 with the motor supply passage 55, andthe drill hammer motor is running, pressure fluid may flow from the valve chamber 43', through port 18, groove ll, passage 1li, groove 'l5 on the valve 44, port 14 and passage "l2, to the bore 'Hl to act on the plunger lock 59 to move the latter inwardly within a locking groove 19 on the valve stem 45. The plunger lock positively locks the valve 44 against movement until? theA supply of' pressure fluid to the hammer motor is= cut off' by the throttle valve' 43. The plunger lock bore '10i may be vented by turning the valve 44 into. the position shown in Fig. 9, and at that time the passage 'lf2 is connected by a circumferential groove Sil-on the valve 44 With the groove 65 communicating with the vent port 63. Therefore, when the drill hammer motor is stop-ped and the supporting cylinder is vented, the plunger lock bore isA concurrently vented and the lock released.

In the modification shown in Figs. 19 to 22, inelusive, the drill hammer motor I, feeding means 2:, supportingv and` guiding means 3 and the control valve means 4 are essentially the same as those above described. I'n this construction the feeding means is non-reversible and comprises a reciprocable feed cylinder 85 by which the drill hammer motor is carried and which contains a feed piston 86 having a tubular piston rod El closed at its rear end by a head 88 threaded thereon. Threadedly secured to this head is an abutmentv engaging point 89 providing the rear support for the drill. A ange on a plug 99 isclamped against the rear end of the feed cylinder` by the head 83's and thisplug is held against rotationwith; respect to the cylinder by a doWel pin 9|. The forward portion of the feed cylinder is received-in a bore 92 in a lateral projection 93 integral with the front chuck housing 8, and the front end of the feed cylinder has a flange 94 clamped against a shoulder $5 by a sleeve 9% engagedl by a detachablehead 9"! in a manner similar to that above described. The piston rod 8l hasa bore 98 containing a reciprocable piston` QS having its piston. rod lili) telescopcally arranged Within the feed cylinder and feed piston rod and' extending forwardly through axial openings in.

the: feed piston andfront cylinder' head. Secured tothe front end of the piston rod Inf! is an abutment. engaging point' lill engageable With the Working face to provide the front support for the drill'. The feed piston 86: carries a packing 02sealingly' engaging the exterior of the piston rod m0? While the front cylinder head contains similar packings H33. Pressure fluid may be supplied to the feeding means in the same manner as in. the form of the invention above described, and pressure fluid may be conducted under the control of the throttle Valve 44 through passage 52, passages in the cylinder and chuck housing and the port 53, to the front end of the feed cylinder bore at the forward side of the feed piston 86. Pressure fluid may be supplied to the bore of' the feed" piston rod under the control of the' valve 44 through passage 63- whichA is now connected through a passage |64 to a recess H35' in the-rear head block of the drill hammer motor. This recess is connected through a exible conduit lfliilto a recess lill' formed in a rear head m3 threadedly secured at 1519i to the rear end of the feed cylinder $5; The head i538 carries packingslili-'93 sealingly engagingI the exterior of the piston rod, and the recess lill is connected by a passage l Il and a port' H22 to the rear end of the feed cylinder bore at the rear side of the feed piston. IlJressureE fluid' may1 flow forwardly through the feed cylinderbore and throng-h a port |23 connected Witha bore l-l 4 formed in the body of the feed piston 86e Threadedly secured at M5 Within the feedj piston body isla conduit l i5 fer connecting the bore H4to'V a bore li? formed in the rear plug 99. The conduit HS' extends through an opening I-lf formed in the piston 99. The bore lil-1" communicates with a recess lle in the rear piston rodhead 88;' and this recess is connected through anaxial passage l2 in the plug 94 with the bore of the feed piston rod 8l at the rear side of the piston 99. From the foregoing it is evident that when the control valve 44 is properly positioned, pressure fluid may flow through passages 63 and |04, recess |35, conduit |06, passage port H2, through the feed cylinder bore and through port ||3, bore H4, conduit H6, bore lll, recess ||9 and passage |29 to the bore of the piston rod, the pressure fluid acting on the rear pressure area of the piston 99 to move the piston rod |08 forwardly to bring the abutment engaging point lill into firm engagement with the working face, Pressure fluid may then be supplied, under the control of the throttle valve 40, through passage 52', passages in the cylinder and chuck housing and port 53 to the forward end of the feed cylinder at the forward side of the feed piston, pressure fluid acting on the rear pressure area of the front cylinder head to feed the feed cylinder, together with the drill hammer motor, forwardly toward the work. The feed cylinder and piston rod bores may be vented to atmosphere under the control of the valves 40 and 44, in the manner described. Otherwise this embodiment of the invention is the same as that above described.

The mode of operation of the preferred embodiment of the invention will be clearly apparent from the description given. The drill is operated in the man ner of a conventional stoper rock drill with the operator grasping a supporting handle |2| projecting laterally from one side of the hammer motor cylinder and the rear end abutment point placed in engagement with a suitable extraneous abutment. Pressure fluid may then be supplied to the supporting cylinder 22 to effect forward movement of the supporting rod 21 to bring the abutment engaging point 29 into engagement with the Working face so that the rock drill is firmly supported at its opposite ends at remotely spaced points. Pressure fluid may then be supplied to the feed cylinder to feed the feed cylinder, together with the drill hammer motor, forwardly properly to position the drill steel with respect toy the working face, and the throttle valve is then operated to effect starting of the motor, and upon a continued supply of pressure fluid to the feed cylinder the drill hammer motor is fed forwardly toward the work to effect its drilling function. When it is desired to reverse the feed, for instance to change drill steels, the feed cylinder is vented in the manner above described so that the drill hammer motor moves rearwardly to release the shank of the drill steel from the chuck housing, and thereafter the operator by grasping the supporting handle |2| swings the drill hammer motor laterally about the alined axes of the piston rods I2 and 2`| so that the drill steel may be withdrawn from the drill hole. A new drill steel is inserted in the drill hole and thereafter the drill hammer motor is swung into its initial position so that the steel shank is received within the chuck housing, and pressure fluid is then again supplied to the feed cylnder to effect forward feeding of the hammer motor toward the work. During the drilling operation the fluid actuated plunger lock 69 locks the valve 44 against movement so that inadvertent venting of the cylinder 22 and the dropping away of the supporting rod 21 from the work is prevented. In this modified Yform of the invention the drill operates in a manner generally similar to that above described in that the supporting rod lil supports the drill against the working face and the feed cylinder and hammer may move back and forth relative to the supporting and guiding means. However, in this form the reverse feed feature is not present.

As a result of this invention it will be noted that an improved rock drill is provided having improved supporting and guiding means for the drill hammer motor whereby the drill is supported both at its rear and front ends against extraneous abutments, such as the mine floor and working face. It will further be evident that by the provision of the improved supporting and guiding structure for the drill hammer motor an improved stoper rock drill of the selfsupported type is provided whereby the falling away of the drill from the working face, even when the supporting handle of the drill is released by the operator or in the event of a broken drill steel, is prevented, as a result reducing the possibility of injury to the operator. It will further be evident that by the provision of the improved fluid supply and control means the means for conducting pressure fluid to the feeding and supporting cylinders is not only simplied but also the fluid supply control is improved. By the provision of the differential pressure areas on the pistons of the preferred embodiment, the feed is automatically reversed whenever the forward feed is vented, thereby eliminating manual reversing of the drill hammer motor, and by the provision of the safety lock for the control valve of the supporting means, accidental dropping away of the supporting means from the work during running of the hammer motor is prevented. It will also be evident that by supplying pressure fluid to the supporting means by means movable within the hammer motor, all external supply connections to the rear end of the piston rod as in previous devices, are eliminated. Other uses and advantages of the improved rock drill will be clearly apparent to those skilled in the art.

While there are in this application specifically described two forms which the invention may assume in practice, it will be understood that these forms of the same are shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a rock drill, the combination comprising an elongated extensible supporting and guiding structure for supporting the rock drill against extraneous abutments at its remote extremities and actuated by pressure fluid, a drilling motor, fluid actuated feeding means associated with said supporting and guiding structure and including a feeding element surrounding and movable along said supporting and guiding structure for feeding said motor toward the work, said feeding element being rotatable about the longitudinal axis of said supporting and guiding structure to swing said motor out of line with the drill hole, means for supplying pressure fluid to said feeding means, and means including a fluid supply connection at least in part arranged within and movable with said feeding element for supplying pressure iluid to said supporting and guiding structure.

2. In a rock drill, the combination comprising an elongated extensible supporting and guiding structure for supporting the rock drill against extraneous abutments at its remote extremities and actuated by pressure fluid, a drilling motor, fluid actuated feeding means associated with said supporting and guiding structure and including a feeding element surrounding and movable along said supporting and guiding structure for feed- .ing said motor toward the work, means :for supplying pressure fluid to said feeding means, means including a fluid supply connection at least in part arranged within and movable with said feeding element for supplying pressure fluid to said supporting and guiding structure, and means associated with an element of said feeding Imeans for mounting said drilling motor on said supporting and guiding structure providing for movement of said motor along said structure .and for swinging movement of said motor out of line with the drill hole.

3. In a rock drill, the combination comprising an elongated extensible supporting structure including relatively reciprocable cylinder and piston elements for supporting the rock drill against extraneous abutments at its remote extremities, a drilling motor, fluid actuated means for feeding said motor along said supporting and guiding structure comprising a reciprocable feed cylinder surrounding said cylinder and piston elements and containing a feed .piston secured to one of said elements, said feed cylinder being rotatable about the longitudinal axis of said supporting structure to swing said motor out of line with the drill hole, means for supplying pressure fluid to said feed cylinder, and means for supplying pressure fluid through at least a portion of said feed cylinder to said cylinder element.

4. In a rock drill, the combination comprising an elongated extensible supporting structure including relatively reciprocable cylinder and piston elements for supporting the rock drillagainst extraneous abutments at its remote extremities, a drilling motor, fluid actuated means for feeding said motor along said supporting and guiding structure comprising a reciprocable feed cylinder surrounding said cylinder and piston elements and containing a feed piston secured to one of said elements, means for supplying pressure fluid to said feed cylinder, means for supplying pressure fluid through at least a portion of said feed cylinder to said cylinder element, and means associated with said feed cylinder for mounting said drilling rnotor on said supporting structure providing for movement of said motor along said structure .and for swinging movement of said motor out of line with the drill hole,

5. In a rock drill, the combination comprising a pressure fluid actuated extensible supporting structure for supporting the drill against eX- traneous abutments at its remote extremities, a drilling motor, fluid actuated feeding means associated with said supporting structure and including a feeding element surrounding and movable along said supporting structure for feeding said motor toward the work, means for supplying pressure fluid to said supporting structure to extend the latter, and means for supplying pressure fluid to and venting pressure fluid from said feeding element, said feeding element, upon supply of pressure fluid thereto, effecting forward feed of said motor, and said supporting structure including an element operative upon pressure fluid supply thereto and venting of said feeding element to effect reverse feed of said motor.

6. In a rock drill, the combination comprising a pressure fluid actuated `extensible supporting structure including relatively reciprocable 'cylinder and piston elements for supporting Vthe drill against extraneous abutments at its remote extremities, a drilling motor, fluid actuated feeding means associated with said supporting structure and including a feed cylinder surrounding and movable along said supporting structure for feeding said motor toward the work, means for supplying pressure fluid to the cylinder `element of said supporting structure to extend the latter, and means for supplying pressure fluid to and venting pressure fluid from said feed cylinder, said feed cylinder, upon supply of pressure fluid thereto, effecting forward feed of said motor, and one of said cylinder and piston elements being operative upon pressure fluid supply thereto and venting of said feed cylinder Vto effect reverse feed of said motor.

7. n a rock drill, the combination comprising a reciprocabie feed cylinder having a front head, a drilling motor carried by said cylinder, a feed piston contained in said cylinder andhaving a tubular piston rod extending rearwardly through the rear end of said cylinder and engageable at its rear end with an extraneous abutment, a support cylinder telescopically arranged within said piston rod and secured at its front end to the front head of said feed cylinder, said support cylinder having a rear piston head providing a rear pressure area and a front pressure area, a supporting rod contained in said support cylinder and extending forwardly through the front head of said feed cylinder and engageable at its front end with the face of the Work being drilled, means for supplying pressure fluid to saidsupport cylinder for moving said supporting rod forwardly into engagement with the working face, means for supplying pressure fluid to said feed cylinder and to the bore of said tubular piston rod, the pressure fluid acting concurrently on the front end of said feed cylinder and in the piston rod bore to act on the rear pressure areas of said front cylinder head and the rear piston head of said support cylinder to effect forward movement of said feed and support cylinders, and means for concurrently venting the fluid acting on said rear pressure areas, the fluid in said support cylinder acting on said front pressure area of said support cylinder head effecting retraction of said support cylinder and feed cylinder when said venting occurs.

8. In a rock drill, the combination comprising a fluid actuated extensible support engageable at its remote extremities with extraneous abutments, a drilling motor, means associated with said support and including a fluid actuated feeding cylinder guided on said support for feeding said motor forwardly toward the work, means for supplying pressure fluid to said support to extend the latter and for subjecting said feeding cylinder to a rearwardly acting pressure, and means for supplying pressure uid to said feeding means to effect forward feeding movement of said feeding cylinder in opposition to said rearwardly acting pressure, and means for venting said feeding means, said rearwardly acting pressure effecting retraction of said motor from the work when said feeding means is vented.

9. In a rock drill, the combination comprising a, drilling motor, and fluid actuating feeding means for effecting feed of said motor forwardly toward the work and. for retracting said motor, said feeding and retracting means including feeding and retracting elements having differential pressure areas, the retracting area being less than the forward feeding area, means for constantly subjecting said retracting pressure area to the action of pressure fluid during the feeding operation, and means for supplying pressure fluid to and venting fluid from said forward pressure area, the pressure fiuid acting on said forward pressure area overcoming the pressure fiuid acting on said retracting pressure area to effect forward feed of said motor, and said retracting pressure area, when the fluid acting on said forward pressure area is vented, effecting retraction of said motor.

10. In a rock drill, the combination comprising a drilling motor, fluid actuated extensible supporting means engageable at its remote extremities with extraneous abutments, and fluid actuated feeding means associated with said supporting means for feeding said motor forwardly and rearwardly along said supporting means toward and from the work, means for supplying pressure fluid to said supporting means to extend the latter and for concurrently subjecting said feeding means to a reverse feeding pressure, and means for supplying pressure fluid to said feeding means to effect forward feed of said motor including means for subjecting said feeding means to a forward feeding pressure of greater magnitude than said reverse feeding pressure, and means for venting said feeding means when the uid supply thereto is cut off thereby to discontinue said forward feeding pressure, said reverse feeding pressure effecting reverse feed of said motor when said forward feeding pressure is vented.

11. In a rock drill, the combination comprising a drilling motor, an extensible support along which said motor is movable during feed thereof, said support having a forwardly movable supporting element engageable with an extraneous abutment, means for feeding said motor along said support including a forwardly movable feeding element, and means movable with said feeding element and having a limiting portion with which said forwardly movable supporting element is engageable for limiting forward movement of said supporting element, said limiting means being secured to said feeding element at the end thereof remote from its limiting portion.

12. In a rock drill, the combination comprising a drilling motor, a uid actuated extensible support engageable with extraneous abutments at its remote extremities, fluid actuated feeding f means associated with said support for feeding said motor therealong and including a feeding element surrounding and movable along said support for feeding said motor toward the work, means associated with an element of said feeding means for mounting said motor on said support providing for movement of said motor along said support and for swinging movement about the longitudinal axis of said support to move said motor out of line with the drill hole, and means carried by said motor and connected to said feeding element of said feeding means near the forward end thereof for supplying pressure fluid to both said support and said feeding means.

13. In a rock drill, the combination comprising a drilling motor, a fluid actuated extensible support engageable with extraneous abutments at for swinging movement therewith about the longitudinal axis of said support out of line with the drill hole, and means carried by said motor and connected to said movable one of said cylinder and piston elements for supplying pressure fluid to both said support and said feeding means.

14. In a rock drill, the combination comprising a drilling motor, cylinder means having concentric coextensive bores, a piston contained in one of said bores and acting in a rearward direction, a second piston'contained in said other bore and acting in a forward direction, means for supplying pressure fluid to said bores to effect forward feed of said motor, means for venting said bores, and means for subjecting said second piston to a reverse feeding pressure to effect reverse feed of said motor when said bores are vented.

15. In a rock drill, the combination comprising a drilling motor, cylinder means having concentric coextensive bores, a piston contained in one of said bores and acting in a rearward direction, a second piston contained in another bore and acting in a forward direction, and a forwardly acting piston contained in a third bore, means for supplying pressure fluid to said first and second bores to effect forward feeding of said motor, means for venting said first and second bores, means for subjecting said second piston to a reverse feeding pressure to effect reverse feed of said motor when said first and second bores are vented, and means for supplying pressure fluid to said third bore to subject the piston therein to a forward feeding pressure to effect forward movement thereof.

16. In a rock drill, the combination comprising a drilling motor, a reciprocable feed cylinder by which said motor is carried, a feed piston contained in said cylinder and having a rearwardly extending tubular piston rod engageable at its rear end with an extraneous abutment, a second cylinder arranged concentrically within and secured to said feed cylinder, said second cylinder contained in the bore of said feed piston rod and having a piston at its rear end, a third piston v contained in said second cylinder and having a forwardly extending piston rod engageable at its front end with an extraneous abutment, means for supplying pressure uid to said second cylinder to effect forward movement of said third piston, and means for concurrently supplying pressure fiuid to the forward end of said feed cylinder in advance of said feed piston and to the rear end of said piston rod bore at the rear side of said second piston to effect forward feed of said motor, and means for venting said ends of said feed cylinder and said piston rod bore, the pressure fiuid in said second cylinder acting to move said second piston rearwardly when said venting occurs to effect reverse feed of said motor.

17. In a rock drill, the combination comprising a drilling motor, a fluid actuated extensible support engageable with extraneous abutments at its remote extremities, and iiuid actuated means for feeding said motor along said support toward the work including a fiuid actuated feeding element surrounding and movable along said support during feeding and rotatable about the longitudinal axis of said support to swing said motor out of line with the drill hole, means for supplying pressure uid to said feeding means, and means for supplying pressure fluid to said support including a fluid supply connection with said movable feeding element.

18. In a rock drill, the combination comprising a drilling motor, a fiuid actuated extensible support engageable with extraneous abutments at its remote extremities, and fluid actuated means for feeding said motor along said support toward the work including a fluid actuated feeding element movable along said support during feeding, means for supplying pressure fluid to said feeding means, and means for supplying pressure uid to said support including a fluid supply connection with said movable feeding element at the rear end of the latter, the pressure fluid flowing from said supply connection forwardly within said feeding element, and means within said feeding element for conducting the fluid in a rearward direction and operatively connected to the rear end of said support.

19. In a rock drill, the combination comprising a drilling motor, a reciprocable feed cylinder by which said motor is carried, a feed piston contained in said cylinder and having its piston rod extending rearwardly through the rear end of said cylinder into engagement with an extraneous abutment, said piston rod having a bore, a reciprocable piston contained in said piston rod bore and having its piston rod extending forwardly through the front end of said feed cylinder into engagement with an extraneous abutment, means carried by said motor for supplying pressure fluid to the front end of said feed cylinder at the front side of said feed piston to effect forward feed of said motor, and means carried by said motor for supplying pressure fluid to the rear end of said piston rod bore at the rear side of said reciprocable piston to effect forward movement of its piston rod into engagement with its extraneous abutment, said last mentioned fluid supply means having a supply connection with said feed cylinder at the rear side of said feed piston.

20. In a rock drill, the combination comprising a drilling motor, a reciprocable feed cylinder by which said motor is carried, a feed piston contained in said cylinder and having its piston rod extending rearwardly through the rear end of said cylinder into engagement with an extraneous abutment, said piston rod having a bore, a reciprocable piston contained in said piston rod bore and having its piston rod extending forwardly through the front end of said feed cylinder into engagement with an extraneous abutment, means carried by said motor for supplying pressure fluid to the front end of said feed cylinder at the front side of said feed piston to effect forward feed of said motor, and means carried by said motor for supplying pressure fluid to the rear end of said piston rod bore at the rear side of said reciprocable piston to effect forward movement of its piston rod into engagement with its extraneous abutment, said last mentioned fluid supply means having a supply connection with said feed cylinder at the rear side of said feed piston and including a conduit extending longitudinally within said piston rod for conducting the pressure fluid from the feed cylinder bore to the rear end of said piston rod bore.

21. In a rock drilling apparatus, relatively reciprocable feed cylinder and feed piston elements, said feed piston element having a piston rod extending through one end of said feed cylinder element, a drilling motor fixed to one of said elements, fluid actuated means coaxial with said cylinder and piston elements for supporting said drill on the working face including a fluid actuated supporting element reciprocably mounted with respect to both of said cylinder.

and piston elements, an abutment fixed relative to the one of said cylinder and piston elements to which the drilling motor is not xed, and controlling means for said apparatus including means common to the space between said piston rod and cylinder element and to said uid actuated drill supporting means for selectively supplying fluid to and venting both of the same.

22. In a rock drill, the combination comprising a fluid actuated extensible support engageable with the working face, a drill hammer motor guided for movement along said support, means for supplying pressure fluid to said support to extend the latter, and means operative only during running of said motor for precluding release of said support from the working face, said means being releasable only upon stopping of said motor.

23. In a rock drill, the combination comprising a fluid actuated extensible support engageable with the working face, a drill hammer motor guided for movement along said support, means for supplying pressure uid to said support to extend the latter, said supplying means including a supply controlling element, and means operative only during running of said motor for precluding release of said support from the working face and including fluid actuated locking means for said supply controlling element, said locking means being releasable only upon stopping of said motor.

ELMER G. GARTIN. 

